The present application is a continuation of International Application No. PCT/SE2004/001630, filed Nov. 9, 2004, designating the U.S., and claiming priority to SE 0302992-3, filed Nov. 10, 2003, both of which are incorporated by reference.
The present invention relates to a working machine, comprising a frame, a cab arranged on the frame, and a lateral support means arranged between the frame and the cab for taking up load from the cab to the frame when lateral displacement of the cab takes place in a direction toward the side on which the lateral support means is arranged.
The working machine can be any type of working machine which comprises a cab. In particular, a type of machine is intended where the cab is spring-mounted on the frame, as is typical of excavating machines. For the purpose of exemplification, the invention will therefore be described with reference to an excavating machine of such a kind.
The invention relates in particular to a working machine in which the cab is laterally mounted on the frame and forms the structural part which, in the event of the machine overturning in one lateral direction at least, will be directly subjected to considerable lateral forces.
During normal operation, cabs of excavating machines are not subjected to any appreciable lateral forces. It does happen, however, that excavating machines, for example in connection with excavating on steeply sloping ground, are subjected to such great lateral forces that they overturn in the lateral direction.
Such excavating machines usually comprise an arm extending from the frame for controlling the actual implement, the bucket. The arm is mounted alongside the cab and is, together with the cab, arranged rotatably or at least pivotably in the horizontal plane of the machine. In other words, it is always located at the side of the cab.
If tipping or overturning takes place in the direction toward the arm, the arm will take up a large part of the lateral forces to which it is subjected on impact with the ground. The cab can come to rest with its dead weight against the arm and possibly also to some extent against the ground but will not in normal cases be subjected to particularly great lateral forces in the event of overturning in this direction.
If the machine overturns in the direction where no arm protects the cab from lateral forces, great lateral forces will be applied to the cab. Modern cab constructions are not always sufficiently strong to take up such large forces as may be involved, at least in the case of larger excavating machines.
One way of solving the problems referred to above is described in JP 2002-46657. This document discloses a reinforcement construction or a protective construction on a vehicle which, to judge from the abstract and the drawing, is a dumper, excavating machine or the like.
The cab is laterally located, that is to say offset relative to the center axis of the vehicle. A stay is fixed between the frame and the cab, probably for taking up lateral forces between the cab and the frame.
One disadvantage of the construction disclosed in JP 2002-46657, however, is that the stay is apparently rigidly connected to on the one hand the frame and on the other hand the cab. It is not clear whether the cab in JP 2002-46657 is spring-mounted. If that were the case, the stay construction shown would have a marked detrimental effect on the mounting of the cab and the comfort the driver would enjoy during operation.
Vibrations and shaking which normally occur in the frame and the chassis would be transmitted to the cab via the stay.
It is desirable to provide a working machine of the kind referred to in the introduction which is constructed in such a way that its cab is relieved in the event of overturning. In other words, the working machine is to be provided with a support construction for taking up the lateral forces to which the cab is subjected in connection with overturning in at least one of two lateral directions.
The support construction is moreover to allow spring-mounting of the cab during normal operation, that is to say it is not to transmit vibrations and shaking from the frame or the chassis to the cab.
According to an aspect of the present invention, a working machine comprises lateral support means arranged to allow an initial lateral displacement of the cab before its function of taking up load is activated. If the cab is laterally located, that is to say offset from the center line of the working machine, the lateral support means is advantageously located on that side of the cab nearest to said center line.
According to an aspect of the invention, the lateral support means is arranged directly in front of a beam of the cab so as, when lateral displacement takes place, to bear against and take up load directly via said beam. The beam is preferably a vertical beam of the cab or a horizontal beam of the cab. It is also conceivable for the lateral support means to be arranged directly in front of both a vertical beam and a horizontal beam, suitably located at the upper edge of the cab or at the lower edge of a side window. In a preferred embodiment, the vertical beam is a front beam, but it would for that matter be conceivable for the lateral support means to be arranged directly in front of a rear vertical beam.
However, these beams can often be made relatively strong without having any appreciable detrimental effect on the field of vision of the driver. In a normal case, therefore, the rear vertical beam is considerably stronger, that is to say it has a greater capacity for taking up load, than the front vertical beam, which in turn results in it being the front vertical beam which has to be reinforced by way of the lateral support means in order to avoid the front beam giving way and the front portion of the cab collapsing.
Generally, the lateral support means should be arranged directly in front of that part of the cab, or the beam, which runs the greatest risk of collapsing in the event of overturning as described above. This is normally the weakest of a number of beams which are present.
The lateral support means is suitably anchored to the frame. According to an aspect of the invention, the working machine comprises an arm mounted in the frame at the side of the cab, the lateral support means advantageously being anchored to the arm. The arm is a swiveling arm for controlling and maneuvring an implement, typically a bucket or the like.
The lateral support means is advantageously arranged with a free clearance between itself and the cab. The clearance should be greater than the expected lateral movements of the cab during normal operation in the region of the lateral support means. According to an aspect of the invention, however, the lateral support means is spring-anchored to the cab.
The spring action should be so gentle that vibrations and shaking from the frame or the chassis during normal operation are not transmitted to the cab via the lateral support means. Alternatively, the lateral support means can be fixed to the cab and have a clearance toward the frame so as, when the cab is displaced in the lateral direction, to be supported against the frame or a part connected thereto, such as the arm of an excavating machine.
The lateral support means is suitably dimensioned to be deformed while it takes up load from the cab to the frame and thus allow limited continued lateral displacement of the cab. The deformation can be only elastic or elastic which changes to plastic. The deformation is to be such that it counteracts early collapse of the cab in the event of overturning. The lateral support means can be said to form a deformation zone for the cab.